Grabs the item's data from the instance's storage system.
{"msg":"get_storage","instance_guid":"my_session_id_here","Item":"foo","passkey":"insert password here","role_id":"superadmin"}

The server will send the item's data to the client:
{"MSG":"got_storage","Item":"foo","Data":"bar"}

If the Item's password is incorrect:
{"MSG":"incorrect_storage_password"}

If the item is not found:
{"MSG":"item_not_found"}